1. Field of the Invention
The present invention relates to a system of electronic reprographics and, more particularly, to a system of electronic reprographics which performs printer dynamic job recovery without any loss in job integrity.
2. Description of the Related Art
In light lens printing systems, a lamp or flashing unit flashes light on a document and has an image created synchronously on a photoreceptor belt. The photoreceptor belt picks up toner from which a copy is made.
In electronic reprographic printing systems, a document or series of documents comprising at least one print job are successively scanned. Upon scanning of the documents, image signals are obtained and electronically stored. The signals are then read out successively and transferred to a printer for formation of the images on paper. Once a document is scanned, it can be printed any number of times or processed in any number of ways (e.g., words deleted or added, image magnified or reduced, etc.). If a plurality of documents comprise a job which is scanned, the processing or manipulation of the scanned documents can include deletion of one or more documents, reordering of the documents into a desired order, or addition of a previously or subsequently scanned document or documents. The printing or processing can be relatively synchronous with scanning, or asynchronous after scanning. If asynchronous, a time interval exists between scanning and printing or processing. The system can then accumulate a number of scanned jobs in the system memory for subsequent processing or printing. The order of the jobs to be printed may be different from the order of jobs as scanned depending on the priority of the jobs and the desires of the operator for increasing productivity or through-put and decreasing printer or scanner down-time.
For a variety of reasons, the printed job may include sheets having images of questionable integrity. This can be the result of a system fault, a Raster Output scanner fault causing a failure to image properly, paper misfeed or misregistration, lack of communication between the Raster, Output scanner and control system, etc.
The related art has disclosed printing systems which include job recovery including sheet purging.
U.S. Pat. No. 4,327,993 to Gauronski et al discloses a method and apparatus for performing job recovery in a reproduction machine wherein purge sheets are sent to a tray not currently in use or to a tray which contains the rest of a copy job. When the purged sheets are sent to the tray which contains the copy job, they must be separated from the copy job once copying is complete.
U.S. Pat. No. 4,206,996 to Clark et al discloses a job recovery method and apparatus wherein duplex job recovery is accomplished by purging all sheets, optionally flagging missing copies by inserting blank sheets into the copy job and then rerunning the copy job as necessary.
There have thus been attempts to remedy the presence of such sheets by providing the systems with the capability to initially purge themselves well prior to the required sheet and initiate job recovery prior to the required sheet after the control system waits for all possible purge sheets in the paper path to be delivered. Operator attention is required, and there is a loss of job integrity caused by the inability to recover to the correct sheet.